Woven fabrics of a nylon fiber or a polyester fiber have been used in the past as a reinforcing layer of conveyor belts.
However, the conveyor belt of this kind is likely to be damaged due to abnormal deformation that occurs when foreign matters such as a cake adhering to pullies and falling transported materials are caught between the pullies and the conveyor belt. Even though abnormal deformation is not of the level which directly results in the damage of the belt, repetition of such abnormal deformation lowers the strength of the belt due to its fatigue and consequently, the conveyor belt cannot withstand an extended use.
In the conveyor belt of this kind, elongation occurs in a longitudinal direction of the belt in the course of use of the belt, and the belt is elongated as a whole. In such a case, the length of the conveyor machine must be regulated by adjusting the stroke of a take-up device disposed in front, or at the back, of the belt conveyor machine. As this elongation proceeds further and the stroke of the take-up device cannot absorb the elongation any longer, the belt must be cut short.
Consequently, the inventors of the present invention have examined from various aspects the damage and fatigue of the conveyor belt resulting from the abnormal deformation that occurs when any foreign matters are caught between the pullies and the conveyor belt, and means for reducing the elongation of the belt that occurs in the course of use. As a result, the present inventors have found it effective to increase, as much as possible, elongation at break of a synthetic fiber woven fabric constituting a reinforcing layer of a conveyor belt in the belt longitudinal direction to cope with the breakage and the fatigue of the belt resulting from abnormal deformation, and to reduce, as much as possible, the elongation of the synthetic fiber woven fabric in the belt longitudinal direction during its use to cope with the elongation of the belt.